1. Field of the Invention
This invention relates generally to gas fractionalization systems and, in particular, to systems and methods for monitoring and controlling the gas fractionalization system to provide consistency and reliability in system performance over time.
2. Description of the Related Art
The application of oxygen concentrators for therapeutic use is known, and many variants of such devices exist. A particularly useful class of oxygen concentrators is designed to be portable, allowing users to move about and to travel for extended periods of time without the need to carry a supply of stored oxygen. Most of these portable concentrators produce an oxygen-rich gas by feeding compressed air through a pressure swing adsorption (PSA) system which selectively removes nitrogen and other components in the air so as to produce a pressurized, oxygen-rich product gas.
Generally, the design of such portable concentrators should be small, lightweight and quiet to be effective. One of the elements to achieve these design goals is to optimize the operation of the compressor, which is typically one of the main consumers of power and producers of noise in a concentrator. Compressors capable of variable output have been used to vary the compressor output air flow to match the required product gas output so that power consumption and noise do not exceed what is required to deliver the desired amount of product gas. Such compressors include fixed displacement volume with variable speed control, fixed speed with variable displacement volume control, or combined variable speed/variable displacement designs.
However, it is often difficult to modulate the compressor speed or displacement in a manner that is accurate and reproducible over time to meet the requirements of precise product gas flow rate necessary for therapeutic use. For example, the inventors have found that it is often impractical to obtain large numbers of speed controlled compressors in a desired size/capacity range that all fall within a narrow range of capacity versus flow required for concentrator applications. Consequently, a significant fraction of a lot of compressors often ends up being rejected at the time the concentrators are built and tested. While compressors having tighter tolerances are available, the cost of such compressors is often very high which in turn increases the initial manufacturing cost of portable concentrators. Moreover, the flow performance of compressors with respect to fixed speed or displacement typically change over time due to break-in and wear, which in turn could cause the concentrator to develop out of specification performance as to accuracy of delivery rate.
From the foregoing, it will be appreciated that there is a need for an apparatus and method for effectively providing supplemental oxygen to patients in a consistent and reliable manner. To this end, there is a particular need for oxygen concentrators that are relatively quiet, energy efficient and cost effective, while providing accurate and reliable system performance over time.